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                <h1 id="比赛补题"><a href="#比赛补题" class="headerlink" title="比赛补题"></a>比赛补题</h1><ul>
<li><p><a target="_blank" rel="noopener" href="https://ac.nowcoder.com/acm/contest/11226/">牛客小白月赛49_ACM/NOI/CSP/CCPC/ICPC算法编程高难度练习赛_牛客竞赛OJ (nowcoder.com)</a></p>
</li>
<li><p><a target="_blank" rel="noopener" href="https://codeforces.com/contest/1670">Dashboard - Codeforces Round #788 (Div. 2) - Codeforces</a></p>
</li>
<li><p><a target="_blank" rel="noopener" href="https://codeforces.com/contest/1675">Dashboard - Codeforces Round #787 (Div. 3) - Codeforces</a></p>
</li>
<li><p><a target="_blank" rel="noopener" href="https://codeforces.com/contest/1674">Dashboard - Codeforces Round #786 (Div. 3) - Codeforces</a></p>
</li>
<li><p><a target="_blank" rel="noopener" href="https://codeforces.com/contest/1673">Dashboard - Codeforces Round #785 (Div. 2) - Codeforces</a></p>
</li>
<li><p><a target="_blank" rel="noopener" href="https://leetcode-cn.com/contest/biweekly-contest-77">第 77 场双周赛 - 力扣（LeetCode） (leetcode-cn.com)</a></p>
</li>
</ul>
<h1 id="疑难杂题"><a href="#疑难杂题" class="headerlink" title="疑难杂题"></a>疑难杂题</h1><p>代码源 + cf + 牛客 + atcoder + 知乎严鸽哥</p>
<p><a target="_blank" rel="noopener" href="http://oj.daimayuan.top/course/10/problem/731">数字替换 - 题目 - Daimayuan Online Judge</a></p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">5e5</span>+<span class="number">10</span>;</span><br><span class="line"><span class="keyword">struct</span> <span class="title class_">node</span>{</span><br><span class="line">    <span class="type">int</span> t,x,y;</span><br><span class="line">}q[N];</span><br><span class="line"><span class="type">int</span> mp[N],n;</span><br><span class="line">vector&lt;<span class="type">int</span>&gt;ans;</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">0</span>;i&lt;N;i++)mp[i]=i;</span><br><span class="line">    cin&gt;&gt;n;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">        <span class="type">int</span> t,x,y;</span><br><span class="line">        cin&gt;&gt;t;</span><br><span class="line">        <span class="keyword">if</span>(t==<span class="number">1</span>){</span><br><span class="line">            cin&gt;&gt;x;</span><br><span class="line">            q[i]={t,x};</span><br><span class="line">        }</span><br><span class="line">        <span class="keyword">else</span>{</span><br><span class="line">            cin&gt;&gt;x&gt;&gt;y;</span><br><span class="line">            q[i]={t,x,y};</span><br><span class="line">        }</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=n;i&gt;=<span class="number">1</span>;i--){</span><br><span class="line">        <span class="type">int</span> t=q[i].t;</span><br><span class="line">        <span class="type">int</span> x=q[i].x;</span><br><span class="line">        <span class="type">int</span> y=q[i].y;</span><br><span class="line">        <span class="keyword">if</span>(t==<span class="number">2</span>)mp[x]=mp[y];</span><br><span class="line">        <span class="keyword">else</span> ans.<span class="built_in">push_back</span>(mp[x]);</span><br><span class="line">    }</span><br><span class="line">    <span class="built_in">reverse</span>(ans.<span class="built_in">begin</span>(),ans.<span class="built_in">end</span>());</span><br><span class="line">    <span class="keyword">for</span>(<span class="keyword">auto</span> x:ans)cout&lt;&lt;x&lt;&lt;<span class="string">" "</span>;</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>



<hr>
<p><a target="_blank" rel="noopener" href="http://oj.daimayuan.top/course/10/problem/701">画画 - 题目 - Daimayuan Online Judge</a></p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="type">int</span> n,m;</span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">1100</span>;</span><br><span class="line"><span class="type">int</span> a[N][N];</span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">get</span><span class="params">(<span class="type">int</span> i,<span class="type">int</span> j)</span></span>{</span><br><span class="line">    <span class="keyword">return</span> (i<span class="number">-1</span>)*m+j;</span><br><span class="line">}</span><br><span class="line"><span class="keyword">struct</span> <span class="title class_">node</span>{</span><br><span class="line">    <span class="type">int</span> x,y,c;</span><br><span class="line">}q[N*N];</span><br><span class="line"><span class="type">int</span> xx[]={<span class="number">-1</span>,<span class="number">-1</span>,<span class="number">1</span>,<span class="number">0</span>,<span class="number">1</span>,<span class="number">2</span>,<span class="number">2</span>,<span class="number">2</span>,<span class="number">1</span>,<span class="number">0</span>,<span class="number">1</span>,<span class="number">0</span>,<span class="number">1</span>,<span class="number">2</span>};</span><br><span class="line"><span class="type">int</span> yy[]={<span class="number">-1</span>,<span class="number">0</span>,<span class="number">0</span>,<span class="number">-1</span>,<span class="number">1</span>,<span class="number">-1</span>,<span class="number">0</span>,<span class="number">1</span>,<span class="number">0</span>,<span class="number">1</span>,<span class="number">1</span>,<span class="number">2</span>,<span class="number">2</span>,<span class="number">2</span>};</span><br><span class="line"><span class="type">int</span> dx[]={<span class="number">0</span>,<span class="number">1</span>,<span class="number">0</span>,<span class="number">1</span>};</span><br><span class="line"><span class="type">int</span> dy[]={<span class="number">0</span>,<span class="number">0</span>,<span class="number">1</span>,<span class="number">1</span>};</span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">check</span><span class="params">(<span class="type">int</span> x,<span class="type">int</span> y)</span></span>{</span><br><span class="line">    <span class="type">int</span> p=<span class="number">-1</span>;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> t=<span class="number">0</span>;t&lt;<span class="number">4</span>;t++){</span><br><span class="line">        <span class="type">int</span> i=x+dx[t];</span><br><span class="line">        <span class="type">int</span> j=y+dy[t];</span><br><span class="line">        <span class="keyword">if</span>(i&lt;<span class="number">1</span>||i&gt;n||j&lt;<span class="number">1</span>||j&gt;m)<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">        <span class="type">int</span> c=a[i][j];</span><br><span class="line">        <span class="keyword">if</span>(c==<span class="number">-1</span>)<span class="keyword">continue</span>;</span><br><span class="line">        <span class="keyword">if</span>(p==<span class="number">-1</span>)p=c;</span><br><span class="line">        <span class="keyword">if</span>(c!=p)<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">return</span> <span class="number">1</span>;</span><br><span class="line">}</span><br><span class="line"><span class="type">int</span> vis[N][N];</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    ios::<span class="built_in">sync_with_stdio</span>(<span class="number">0</span>);</span><br><span class="line">    cin&gt;&gt;n&gt;&gt;m;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> j=<span class="number">1</span>;j&lt;=m;j++)cin&gt;&gt;a[i][j];</span><br><span class="line">    }</span><br><span class="line">    <span class="type">int</span> hh=<span class="number">0</span>,tt=<span class="number">0</span>;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> j=<span class="number">1</span>;j&lt;=m;j++){</span><br><span class="line">            <span class="keyword">if</span>(<span class="built_in">check</span>(i,j)){</span><br><span class="line">                q[tt++]={i,j,a[i][j]};</span><br><span class="line">                vis[i][j]=<span class="number">1</span>;</span><br><span class="line">                <span class="comment">//cout&lt;&lt;"i="&lt;&lt;i&lt;&lt;"  j="&lt;&lt;j&lt;&lt;endl;</span></span><br><span class="line">            }</span><br><span class="line">        }</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">if</span>(hh==tt){</span><br><span class="line">        cout&lt;&lt;<span class="string">"-1"</span>;</span><br><span class="line">        <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">    }</span><br><span class="line">    stack&lt;node&gt;ans;</span><br><span class="line">    <span class="keyword">while</span>(hh&lt;tt){</span><br><span class="line">        <span class="keyword">auto</span> t=q[hh++];</span><br><span class="line">        </span><br><span class="line">        ans.<span class="built_in">push</span>(t);</span><br><span class="line">        <span class="type">int</span> x=t.x,y=t.y,c=t.c;</span><br><span class="line">        a[x][y]=<span class="number">-1</span>,a[x+<span class="number">1</span>][y]=<span class="number">-1</span>,a[x][y+<span class="number">1</span>]=<span class="number">-1</span>,a[x+<span class="number">1</span>][y+<span class="number">1</span>]=<span class="number">-1</span>;</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> t=<span class="number">0</span>;t&lt;<span class="number">14</span>;t++){</span><br><span class="line">            <span class="type">int</span> i=x+xx[t];</span><br><span class="line">            <span class="type">int</span> j=y+yy[t];</span><br><span class="line">            <span class="keyword">if</span>(i&lt;<span class="number">1</span>||i&gt;n||j&lt;<span class="number">1</span>||j&gt;m)<span class="keyword">continue</span>;</span><br><span class="line">            <span class="keyword">if</span>(vis[i][j])<span class="keyword">continue</span>;</span><br><span class="line">            <span class="type">int</span> c=<span class="number">-1</span>;</span><br><span class="line">            <span class="comment">//cout&lt;&lt;"i="&lt;&lt;i&lt;&lt;" j="&lt;&lt;j&lt;&lt;endl;</span></span><br><span class="line">            <span class="keyword">if</span>(<span class="built_in">check</span>(i,j)){</span><br><span class="line">                <span class="keyword">if</span>(a[i][j]!=<span class="number">-1</span>)c=a[i][j];</span><br><span class="line">                <span class="keyword">if</span>(a[i+<span class="number">1</span>][j]!=<span class="number">-1</span>)c=a[i+<span class="number">1</span>][j];</span><br><span class="line">                <span class="keyword">if</span>(a[i][j+<span class="number">1</span>]!=<span class="number">-1</span>)c=a[i][j+<span class="number">1</span>];</span><br><span class="line">                <span class="keyword">if</span>(a[i+<span class="number">1</span>][j+<span class="number">1</span>]!=<span class="number">-1</span>)c=a[i+<span class="number">1</span>][j+<span class="number">1</span>];</span><br><span class="line">                <span class="keyword">if</span>(c==<span class="number">-1</span>)c=<span class="number">1</span>;</span><br><span class="line">                q[tt++]={i,j,c};</span><br><span class="line">                vis[i][j]=<span class="number">1</span>;</span><br><span class="line">                <span class="comment">//cout&lt;&lt;"i="&lt;&lt;i&lt;&lt;" j="&lt;&lt;j&lt;&lt;endl;</span></span><br><span class="line">            }</span><br><span class="line">            </span><br><span class="line">        }</span><br><span class="line">    }</span><br><span class="line">    cout&lt;&lt;ans.<span class="built_in">size</span>()&lt;&lt;<span class="string">'\n'</span>;</span><br><span class="line">    <span class="keyword">while</span>(ans.<span class="built_in">size</span>()){</span><br><span class="line">        <span class="keyword">auto</span> t=ans.<span class="built_in">top</span>();</span><br><span class="line">        ans.<span class="built_in">pop</span>();</span><br><span class="line">        cout&lt;&lt;t.x&lt;&lt;<span class="string">" "</span>&lt;&lt;t.y&lt;&lt;<span class="string">" "</span>&lt;&lt;t.c&lt;&lt;<span class="string">'\n'</span>;</span><br><span class="line">    }</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>





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<p><a target="_blank" rel="noopener" href="https://blog.nowcoder.net/n/5f6ff64391d546e38bd17dc1b7448ef1">小雨坐地铁（分层图_牛客博客 (nowcoder.net)</a></p>
<hr>
<p><a target="_blank" rel="noopener" href="http://oj.daimayuan.top/course/10/problem/704">环的数量 - 题目 - Daimayuan Online Judge</a></p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">20</span>,M=<span class="number">1</span>&lt;&lt;N;</span><br><span class="line"><span class="type">int</span> f[M][N],n,m,g[N][N];</span><br><span class="line"><span class="type">long</span> <span class="type">long</span> ans;</span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">lowbit</span><span class="params">(<span class="type">int</span> x)</span></span>{<span class="keyword">return</span> (<span class="type">int</span>)<span class="built_in">log2</span>(x&amp;-x);}</span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">cal</span><span class="params">(<span class="type">int</span> x)</span></span>{</span><br><span class="line">    <span class="type">int</span> cnt=<span class="number">0</span>;</span><br><span class="line">    <span class="keyword">while</span>(x)cnt+=x&amp;<span class="number">1</span>,x&gt;&gt;=<span class="number">1</span>;</span><br><span class="line">    <span class="keyword">return</span> cnt;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    ios::<span class="built_in">sync_with_stdio</span>(<span class="number">0</span>);</span><br><span class="line">    cin.<span class="built_in">tie</span>(<span class="number">0</span>);</span><br><span class="line">    cout.<span class="built_in">tie</span>(<span class="number">0</span>);</span><br><span class="line">    cin&gt;&gt;n&gt;&gt;m;</span><br><span class="line">    <span class="type">int</span> mm=m;</span><br><span class="line">    <span class="keyword">while</span>(m--){</span><br><span class="line">        <span class="type">int</span> a,b;</span><br><span class="line">        cin&gt;&gt;a&gt;&gt;b;</span><br><span class="line">        a--,b--;</span><br><span class="line">        g[a][b]=g[b][a]=<span class="number">1</span>;</span><br><span class="line">        <span class="comment">//f[(1&lt;&lt;a)|(1&lt;&lt;b)][max(a,b)]=1;</span></span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">0</span>;i&lt;n;i++)f[<span class="number">1</span>&lt;&lt;i][i]=<span class="number">1</span>;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;<span class="number">1</span>&lt;&lt;n;i++){</span><br><span class="line">        <span class="type">int</span> u=<span class="built_in">lowbit</span>(i);</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> j=<span class="number">0</span>;j&lt;n;j++){<span class="comment">//j表示我现在走到了点集的哪个点上</span></span><br><span class="line">            <span class="keyword">if</span>(!(i&gt;&gt;j&amp;<span class="number">1</span>))<span class="keyword">continue</span>;</span><br><span class="line">            <span class="keyword">if</span>(g[u][j])ans+=f[i][j];</span><br><span class="line">            <span class="keyword">for</span>(<span class="type">int</span> k=u+<span class="number">1</span>;k&lt;n;k++){<span class="comment">//k表示我现在要走到哪个点</span></span><br><span class="line">                <span class="keyword">if</span>(i&gt;&gt;k&amp;<span class="number">1</span>)<span class="keyword">continue</span>;</span><br><span class="line">                <span class="keyword">if</span>(!g[j][k])<span class="keyword">continue</span>;</span><br><span class="line">                f[i|(<span class="number">1</span>&lt;&lt;k)][k]+=f[i][j];</span><br><span class="line">            }</span><br><span class="line">        }</span><br><span class="line">    }</span><br><span class="line">    cout&lt;&lt;(ans-mm)/<span class="number">2</span>;</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>

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<p><a target="_blank" rel="noopener" href="http://oj.daimayuan.top/course/10/problem/709">最大权值划分 - 题目 - Daimayuan Online Judge</a></p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">1e6</span>+<span class="number">10</span>;</span><br><span class="line"><span class="meta">#<span class="keyword">define</span> int long long</span></span><br><span class="line"><span class="type">int</span> a[N],f[N][<span class="number">2</span>],n;</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    ios::<span class="built_in">sync_with_stdio</span>(<span class="number">0</span>);</span><br><span class="line">    cin&gt;&gt;n;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++)cin&gt;&gt;a[i];</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">2</span>;i&lt;=n;i++){</span><br><span class="line">        <span class="keyword">if</span>(a[i]&lt;a[i<span class="number">-1</span>]){</span><br><span class="line">            f[i][<span class="number">0</span>]=<span class="built_in">max</span>(f[i<span class="number">-1</span>][<span class="number">0</span>]+a[i<span class="number">-1</span>]-a[i],f[i<span class="number">-1</span>][<span class="number">1</span>]);</span><br><span class="line">            f[i][<span class="number">1</span>]=<span class="built_in">max</span>(f[i<span class="number">-1</span>][<span class="number">0</span>],f[i<span class="number">-1</span>][<span class="number">1</span>]);</span><br><span class="line">        }</span><br><span class="line">        <span class="keyword">else</span>{</span><br><span class="line">            f[i][<span class="number">1</span>]=<span class="built_in">max</span>(f[i<span class="number">-1</span>][<span class="number">1</span>]+a[i]-a[i<span class="number">-1</span>],f[i<span class="number">-1</span>][<span class="number">0</span>]);</span><br><span class="line">            f[i][<span class="number">0</span>]=<span class="built_in">max</span>(f[i<span class="number">-1</span>][<span class="number">1</span>],f[i<span class="number">-1</span>][<span class="number">0</span>]);</span><br><span class="line">        }</span><br><span class="line">    }</span><br><span class="line">    cout&lt;&lt;<span class="built_in">max</span>(f[n][<span class="number">0</span>],f[n][<span class="number">1</span>]);</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>

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<p><a target="_blank" rel="noopener" href="http://oj.daimayuan.top/course/10/problem/673">Ayoub’s function - 题目 - Daimayuan Online Judge</a></p>
<p>组合数学+思维</p>
<p><a target="_blank" rel="noopener" href="https://blog.csdn.net/starlet_kiss/article/details/104323776">(8条消息) Ayoub’s function CodeForces - 1301C（组合数学）_starlet_kiss的博客-CSDN博客</a></p>
<hr>
<p><a target="_blank" rel="noopener" href="http://oj.daimayuan.top/course/10/problem/707">括号序列 - 题目 - Daimayuan Online Judge</a></p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line">string s;</span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">1e6</span>+<span class="number">10</span>;</span><br><span class="line"><span class="type">int</span> f[N],match[N];</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    <span class="keyword">while</span>(cin&gt;&gt;s){</span><br><span class="line">        <span class="built_in">memset</span>(f,<span class="number">0</span>,<span class="keyword">sizeof</span> f);</span><br><span class="line">        stack&lt;<span class="type">int</span>&gt;stk;</span><br><span class="line">        <span class="type">int</span> n =s.<span class="built_in">length</span>();</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">            <span class="keyword">if</span>(s[i<span class="number">-1</span>]==<span class="string">'('</span>)stk.<span class="built_in">push</span>(i);</span><br><span class="line">            <span class="keyword">else</span>{</span><br><span class="line">                <span class="keyword">if</span>(stk.<span class="built_in">empty</span>())<span class="keyword">continue</span>;</span><br><span class="line">                <span class="keyword">else</span> match[i]=stk.<span class="built_in">top</span>(),stk.<span class="built_in">pop</span>();</span><br><span class="line">            }</span><br><span class="line">        }</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">            <span class="keyword">if</span>(s[i<span class="number">-1</span>]==<span class="string">')'</span>&amp;&amp;match[i])f[i]=f[match[i]<span class="number">-1</span>]+<span class="number">1</span>;</span><br><span class="line">        }</span><br><span class="line">        </span><br><span class="line">        <span class="comment">// for(int i=1;i&lt;=n;i++){</span></span><br><span class="line">        <span class="comment">//     if(s[i-1]=='(')stk.push(i);</span></span><br><span class="line">        <span class="comment">//     else{</span></span><br><span class="line">        <span class="comment">//         if(stk.empty())continue;</span></span><br><span class="line">        <span class="comment">//         int t=stk.top();</span></span><br><span class="line">        <span class="comment">//         stk.pop();</span></span><br><span class="line">        <span class="comment">//         match[t]=i;</span></span><br><span class="line">        <span class="comment">//     }</span></span><br><span class="line">        <span class="comment">// }</span></span><br><span class="line">        <span class="comment">// for(int i=n;i&gt;=1;i--){</span></span><br><span class="line">        <span class="comment">//     f[i]=f[i-1];</span></span><br><span class="line">        <span class="comment">//     if(s[i-1]=='('&amp;&amp;match[i]!=0)f[i]=f[match[i]+1]+1;</span></span><br><span class="line">        <span class="comment">// }</span></span><br><span class="line">        <span class="type">long</span> <span class="type">long</span> ans=<span class="number">0</span>;</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">            <span class="keyword">if</span>(s[i<span class="number">-1</span>]==<span class="string">')'</span>&amp;&amp;match[i])ans+=f[i];</span><br><span class="line">        }</span><br><span class="line">        cout&lt;&lt;ans&lt;&lt;<span class="string">'\n'</span>;</span><br><span class="line">    }</span><br><span class="line">    </span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>

<hr>
<p><a target="_blank" rel="noopener" href="http://oj.daimayuan.top/course/11/problem/677">弗拉德和糖果 II - 题目 - Daimayuan Online Judge</a></p>
<p>贪心+小思维</p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;cstring&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;algorithm&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="meta">#<span class="keyword">define</span> int long long</span></span><br><span class="line"><span class="type">int</span> sum,ma,n;</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    ios::<span class="built_in">sync_with_stdio</span>(<span class="number">0</span>);</span><br><span class="line">    cin&gt;&gt;n;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">        <span class="type">int</span> x;</span><br><span class="line">        cin&gt;&gt;x;</span><br><span class="line">        sum+=x;</span><br><span class="line">        ma=<span class="built_in">max</span>(ma,x);</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">if</span>(ma<span class="number">-1</span>&gt;sum-ma)<span class="built_in">puts</span>(<span class="string">"NO"</span>);</span><br><span class="line">    <span class="keyword">else</span> <span class="built_in">puts</span>(<span class="string">"YES"</span>);</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>

<hr>
<p><a target="_blank" rel="noopener" href="http://oj.daimayuan.top/course/11/problem/461">任务分配 - 题目 - Daimayuan Online Judge</a></p>
<hr>
<p><a target="_blank" rel="noopener" href="http://oj.daimayuan.top/problem/737">质区间长度 - 题目 - Daimayuan Online Judge</a></p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">1e6</span>+<span class="number">10</span>;</span><br><span class="line"><span class="type">int</span> primes[N],cnt,st[N],l,r,k,a[N];</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">init</span><span class="params">()</span></span>{</span><br><span class="line">    st[<span class="number">1</span>]=<span class="number">1</span>;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">2</span>;i&lt;N;i++){</span><br><span class="line">        <span class="keyword">if</span>(!st[i])primes[cnt++]=i;</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> j=<span class="number">0</span>;i*primes[j]&lt;N;j++){</span><br><span class="line">            st[primes[j]*i]=<span class="number">1</span>;</span><br><span class="line">            <span class="keyword">if</span>(i%primes[j]==<span class="number">0</span>)<span class="keyword">break</span>;</span><br><span class="line">        }</span><br><span class="line">    }</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">check</span><span class="params">(<span class="type">int</span> mid)</span></span>{</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=l;i&lt;=r;i++){</span><br><span class="line">        <span class="type">int</span> j=i+mid<span class="number">-1</span>;</span><br><span class="line">        <span class="keyword">if</span>(j&gt;r)<span class="keyword">break</span>;</span><br><span class="line">        <span class="keyword">if</span>(a[j]-a[i<span class="number">-1</span>]&lt;k)<span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">return</span> <span class="number">1</span>;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    <span class="built_in">init</span>();</span><br><span class="line">    cin&gt;&gt;l&gt;&gt;r&gt;&gt;k;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=l;i&lt;=r;i++){</span><br><span class="line">        <span class="keyword">if</span>(!st[i])a[i]=a[i<span class="number">-1</span>]+<span class="number">1</span>;</span><br><span class="line">        <span class="keyword">else</span> a[i]=a[i<span class="number">-1</span>];</span><br><span class="line">        <span class="comment">//cout&lt;&lt;i&lt;&lt;" "&lt;&lt;a[i]&lt;&lt;endl;</span></span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">if</span>(a[r]-a[l<span class="number">-1</span>]&lt;k){</span><br><span class="line">        <span class="comment">//cout&lt;&lt;a[r]&lt;&lt;" "&lt;&lt;a[l-1]&lt;&lt;endl;</span></span><br><span class="line">        cout&lt;&lt;<span class="string">"-1"</span>;</span><br><span class="line">        <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">    }</span><br><span class="line">    <span class="type">int</span> L=k,R=r-l+<span class="number">1</span>;</span><br><span class="line">    <span class="keyword">while</span>(L&lt;R){</span><br><span class="line">        <span class="type">int</span> mid=L+R&gt;&gt;<span class="number">1</span>;</span><br><span class="line">        <span class="comment">//cout&lt;&lt;"mid="&lt;&lt;mid&lt;&lt;endl;</span></span><br><span class="line">        <span class="keyword">if</span>(<span class="built_in">check</span>(mid))R=mid;</span><br><span class="line">        <span class="keyword">else</span> L=mid+<span class="number">1</span>;</span><br><span class="line">    }</span><br><span class="line">    cout&lt;&lt;<span class="built_in">max</span>(<span class="number">1</span>,R);</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>

<hr>
<p><a target="_blank" rel="noopener" href="https://www.acwing.com/problem/content/description/4012/">4009. 收集卡牌 - AcWing题库</a></p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;cstring&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;algorithm&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">16</span>,M=<span class="number">1</span>&lt;&lt;N;</span><br><span class="line"><span class="type">int</span> n,k;</span><br><span class="line"><span class="type">double</span> p[N],f[M][N*<span class="number">5</span>+<span class="number">1</span>];</span><br><span class="line"><span class="function"><span class="type">double</span> <span class="title">dfs</span><span class="params">(<span class="type">int</span> x,<span class="type">int</span> sum,<span class="type">int</span> need)</span></span>{</span><br><span class="line">    <span class="keyword">if</span>(f[x][sum]&gt;=<span class="number">0</span>)<span class="keyword">return</span> f[x][sum];</span><br><span class="line">    <span class="keyword">if</span>(sum&gt;=need*k)<span class="keyword">return</span> f[x][sum]=<span class="number">0</span>;</span><br><span class="line">    f[x][sum]=<span class="number">0</span>;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">0</span>;i&lt;n;i++){</span><br><span class="line">        <span class="keyword">if</span>(x&gt;&gt;i&amp;<span class="number">1</span>)f[x][sum]+=p[i]*(<span class="built_in">dfs</span>(x,sum+<span class="number">1</span>,need)+<span class="number">1</span>);</span><br><span class="line">        <span class="keyword">else</span> f[x][sum]+=p[i]*(<span class="built_in">dfs</span>(x^(<span class="number">1</span>&lt;&lt;i),sum,need<span class="number">-1</span>)+<span class="number">1</span>);</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">return</span> f[x][sum];</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    cin&gt;&gt;n&gt;&gt;k;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">0</span>;i&lt;n;i++)cin&gt;&gt;p[i];</span><br><span class="line">    <span class="built_in">memset</span>(f,<span class="number">-1</span>,<span class="keyword">sizeof</span> f);</span><br><span class="line">    cout&lt;&lt;<span class="built_in">dfs</span>(<span class="number">0</span>,<span class="number">0</span>,n);</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>



<hr>
<p><a target="_blank" rel="noopener" href="https://www.acwing.com/problem/content/description/1214/">1212. 地宫取宝 - AcWing题库</a></p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;cstring&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;algorithm&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"></span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N = <span class="number">55</span>, MOD = <span class="number">1000000007</span>;</span><br><span class="line"></span><br><span class="line"><span class="type">int</span> n, m, k;</span><br><span class="line"><span class="type">int</span> w[N][N];</span><br><span class="line"><span class="type">int</span> f[N][N][<span class="number">13</span>][<span class="number">14</span>];</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line">    cin &gt;&gt; n &gt;&gt; m &gt;&gt; k;</span><br><span class="line">    <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>; i &lt;= n; i ++ )</span><br><span class="line">        <span class="keyword">for</span> (<span class="type">int</span> j = <span class="number">1</span>; j &lt;= m; j ++ )</span><br><span class="line">        {</span><br><span class="line">            cin &gt;&gt; w[i][j];</span><br><span class="line">            w[i][j] ++ ;</span><br><span class="line">        }</span><br><span class="line"></span><br><span class="line">    f[<span class="number">1</span>][<span class="number">1</span>][<span class="number">1</span>][w[<span class="number">1</span>][<span class="number">1</span>]] = <span class="number">1</span>;</span><br><span class="line">    f[<span class="number">1</span>][<span class="number">1</span>][<span class="number">0</span>][<span class="number">0</span>] = <span class="number">1</span>;</span><br><span class="line"></span><br><span class="line">    <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>; i &lt;= n; i ++ )</span><br><span class="line">        <span class="keyword">for</span> (<span class="type">int</span> j = <span class="number">1</span>; j &lt;= m; j ++ )</span><br><span class="line">        {</span><br><span class="line">            <span class="keyword">if</span> (i == <span class="number">1</span> &amp;&amp; j == <span class="number">1</span>) <span class="keyword">continue</span>;</span><br><span class="line">            <span class="keyword">for</span> (<span class="type">int</span> u = <span class="number">0</span>; u &lt;= k; u ++ )</span><br><span class="line">                <span class="keyword">for</span> (<span class="type">int</span> v = <span class="number">0</span>; v &lt;= <span class="number">13</span>; v ++ )</span><br><span class="line">                {</span><br><span class="line">                    <span class="type">int</span> &amp;val = f[i][j][u][v];</span><br><span class="line">                    val = (val + f[i - <span class="number">1</span>][j][u][v]) % MOD;</span><br><span class="line">                    val = (val + f[i][j - <span class="number">1</span>][u][v]) % MOD;</span><br><span class="line">                    <span class="keyword">if</span> (u &gt; <span class="number">0</span> &amp;&amp; v == w[i][j])</span><br><span class="line">                    {</span><br><span class="line">                        <span class="keyword">for</span> (<span class="type">int</span> c = <span class="number">0</span>; c &lt; v; c ++ )</span><br><span class="line">                        {</span><br><span class="line">                            val = (val + f[i - <span class="number">1</span>][j][u - <span class="number">1</span>][c]) % MOD;</span><br><span class="line">                            val = (val + f[i][j - <span class="number">1</span>][u - <span class="number">1</span>][c]) % MOD;</span><br><span class="line">                        }</span><br><span class="line">                    }</span><br><span class="line">                }</span><br><span class="line">        }</span><br><span class="line"></span><br><span class="line">    <span class="type">int</span> res = <span class="number">0</span>;</span><br><span class="line">    <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">0</span>; i &lt;= <span class="number">13</span>; i ++ ) res = (res + f[n][m][k][i]) % MOD;</span><br><span class="line"></span><br><span class="line">    cout &lt;&lt; res &lt;&lt; endl;</span><br><span class="line"></span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"></span><br></pre></td></tr></tbody></table></figure>

<hr>
<p><a target="_blank" rel="noopener" href="https://www.acwing.com/problem/content/description/4384/">4381. 翻转树边 - AcWing题库</a></p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N = <span class="number">2e5</span> + <span class="number">10</span>, M = <span class="number">2</span> * N;</span><br><span class="line"><span class="type">int</span> h[N], ne[M], e[M], w[M], idx, dp[N];</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">add</span><span class="params">(<span class="type">int</span> a, <span class="type">int</span> b, <span class="type">int</span> c)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line">    e[idx] = b, ne[idx] = h[a], w[idx] = c, h[a] = idx++;</span><br><span class="line">}</span><br><span class="line"><span class="type">int</span> f[N];</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">dfs1</span><span class="params">(<span class="type">int</span> u, <span class="type">int</span> fa)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line">    <span class="keyword">for</span> (<span class="type">int</span> i = h[u]; i != <span class="number">-1</span>; i = ne[i])</span><br><span class="line">    {</span><br><span class="line">        <span class="type">int</span> j = e[i], k = w[i];</span><br><span class="line">        <span class="keyword">if</span> (j == fa)</span><br><span class="line">            <span class="keyword">continue</span>;</span><br><span class="line">        <span class="built_in">dfs1</span>(j, u);</span><br><span class="line">        f[u] += f[j] + k;</span><br><span class="line">    }</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">dfs2</span><span class="params">(<span class="type">int</span> u, <span class="type">int</span> fa)</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line">    <span class="keyword">for</span> (<span class="type">int</span> i = h[u]; i != <span class="number">-1</span>; i = ne[i])</span><br><span class="line">    {</span><br><span class="line">        <span class="type">int</span> j = e[i], k = w[i];</span><br><span class="line">        <span class="keyword">if</span> (j == fa)</span><br><span class="line">            <span class="keyword">continue</span>;</span><br><span class="line">        dp[j] = dp[u] + (k == <span class="number">1</span> ? <span class="number">0</span> : <span class="number">1</span>) - (k == <span class="number">1</span> ? <span class="number">1</span> : <span class="number">0</span>);</span><br><span class="line">        <span class="built_in">dfs2</span>(j, u);</span><br><span class="line">    }</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>{</span><br><span class="line">    <span class="type">int</span> n;</span><br><span class="line">    cin &gt;&gt; n;</span><br><span class="line">    <span class="built_in">memset</span>(h, <span class="number">-1</span>, <span class="keyword">sizeof</span> h);</span><br><span class="line">    <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>; i &lt; n; i++)</span><br><span class="line">    {</span><br><span class="line">        <span class="type">int</span> a, b;</span><br><span class="line">        cin &gt;&gt; a &gt;&gt; b;</span><br><span class="line">        <span class="built_in">add</span>(a, b, <span class="number">0</span>), <span class="built_in">add</span>(b, a, <span class="number">1</span>);</span><br><span class="line">    }</span><br><span class="line">    <span class="built_in">dfs1</span>(<span class="number">1</span>, <span class="number">-1</span>);</span><br><span class="line">    dp[<span class="number">1</span>] = f[<span class="number">1</span>];</span><br><span class="line">    <span class="built_in">dfs2</span>(<span class="number">1</span>, <span class="number">-1</span>);</span><br><span class="line">    <span class="type">int</span> mx = <span class="number">0x3f3f3f3f</span>;</span><br><span class="line">    <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>; i &lt;= n; i++)</span><br><span class="line">        mx = <span class="built_in">min</span>(mx, dp[i]);</span><br><span class="line">    cout &lt;&lt; mx &lt;&lt; <span class="string">"\n"</span>;</span><br><span class="line">    <span class="keyword">for</span> (<span class="type">int</span> i = <span class="number">1</span>; i &lt;= n; i++)</span><br><span class="line">        <span class="keyword">if</span> (dp[i] == mx)</span><br><span class="line">            cout &lt;&lt; i &lt;&lt; <span class="string">" "</span>;</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"></span><br><span class="line"></span><br></pre></td></tr></tbody></table></figure>

<hr>
<p><a target="_blank" rel="noopener" href="https://www.acwing.com/problem/content/description/3114/">3111. 回转寿司 - AcWing题库</a></p>
<p>值域树状数组，离散化后求值</p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="meta">#<span class="keyword">define</span> int long long</span></span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">3e5</span>+<span class="number">10</span>;</span><br><span class="line"><span class="type">long</span> <span class="type">long</span> a[N],tr[N],n,L,R,ans,tot;</span><br><span class="line">vector&lt;<span class="type">long</span> <span class="type">long</span>&gt;xs;</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">add</span><span class="params">(<span class="type">int</span> x,<span class="type">int</span> c)</span></span>{</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=x;i&lt;N;i+=i&amp;-i)tr[i]+=c;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">long</span> <span class="type">long</span> <span class="title">sum</span><span class="params">(<span class="type">int</span> x)</span></span>{</span><br><span class="line">    <span class="type">int</span> ans=<span class="number">0</span>;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=x;i;i-=i&amp;-i)ans+=tr[i];</span><br><span class="line">    <span class="keyword">return</span> ans;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">get</span><span class="params">(<span class="type">long</span> <span class="type">long</span> x)</span></span>{</span><br><span class="line">    <span class="keyword">return</span> <span class="built_in">lower_bound</span>(xs.<span class="built_in">begin</span>(),xs.<span class="built_in">end</span>(),x)-xs.<span class="built_in">begin</span>()+<span class="number">1</span>;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    cin&gt;&gt;n&gt;&gt;L&gt;&gt;R;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">        cin&gt;&gt;a[i];</span><br><span class="line">        a[i]+=a[i<span class="number">-1</span>];</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">        xs.<span class="built_in">push_back</span>(a[i]);</span><br><span class="line">        xs.<span class="built_in">push_back</span>(a[i]-R<span class="number">-1</span>);</span><br><span class="line">        xs.<span class="built_in">push_back</span>(a[i]-L);</span><br><span class="line">    }</span><br><span class="line">    <span class="built_in">sort</span>(xs.<span class="built_in">begin</span>(),xs.<span class="built_in">end</span>());</span><br><span class="line">    xs.<span class="built_in">erase</span>(<span class="built_in">unique</span>(xs.<span class="built_in">begin</span>(),xs.<span class="built_in">end</span>()),xs.<span class="built_in">end</span>());</span><br><span class="line">    tot=xs.<span class="built_in">size</span>();</span><br><span class="line">    <span class="built_in">add</span>(<span class="built_in">get</span>(a[<span class="number">0</span>]),<span class="number">1</span>);</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">        <span class="type">int</span> x=<span class="built_in">get</span>(a[i]);</span><br><span class="line">        <span class="type">int</span> y=<span class="built_in">get</span>(a[i]-R<span class="number">-1</span>);</span><br><span class="line">        <span class="type">int</span> z=<span class="built_in">get</span>(a[i]-L);</span><br><span class="line">        ans+=<span class="built_in">sum</span>(z)-<span class="built_in">sum</span>(y);</span><br><span class="line">        <span class="built_in">add</span>(x,<span class="number">1</span>);</span><br><span class="line">    }</span><br><span class="line">    cout&lt;&lt;ans;</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>



<p><a target="_blank" rel="noopener" href="https://www.acwing.com/problem/content/description/4319/">4316. 合适数对 - AcWing题库</a></p>
<p>同方法题</p>
<hr>
<p><a target="_blank" rel="noopener" href="https://www.acwing.com/problem/content/description/2662/">2660. 方伯伯的玉米田 - AcWing题库</a></p>
<p>利用树状数组的dp</p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;cstring&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;algorithm&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">1e4</span>+<span class="number">10</span>,M=<span class="number">550</span>;</span><br><span class="line"><span class="type">int</span> tr[M][N],a[N],n,k,ans;</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">add</span><span class="params">(<span class="type">int</span> k,<span class="type">int</span> v,<span class="type">int</span> c)</span></span>{</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=k;i&lt;=<span class="number">551</span>;i+=i&amp;-i){</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> j=v;j&lt;=<span class="number">5500</span>;j+=j&amp;-j){</span><br><span class="line">            tr[i][j]=<span class="built_in">max</span>(tr[i][j],c);</span><br><span class="line">        }</span><br><span class="line">    }</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">sum</span><span class="params">(<span class="type">int</span> k,<span class="type">int</span> v)</span></span>{</span><br><span class="line">    <span class="type">int</span> ans=<span class="number">0</span>;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=k;i;i-=i&amp;-i){</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> j=v;j;j-=j&amp;-j){</span><br><span class="line">            ans=<span class="built_in">max</span>(ans,tr[i][j]);</span><br><span class="line">        }</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">return</span> ans;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    ios::<span class="built_in">sync_with_stdio</span>(<span class="number">0</span>);</span><br><span class="line">    cin.<span class="built_in">tie</span>(<span class="number">0</span>);</span><br><span class="line">    cout.<span class="built_in">tie</span>(<span class="number">0</span>);</span><br><span class="line">    cin&gt;&gt;n&gt;&gt;k;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++)cin&gt;&gt;a[i];</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> j=k;j&gt;=<span class="number">0</span>;j--){</span><br><span class="line">            <span class="type">int</span> t=<span class="built_in">sum</span>(j+<span class="number">1</span>,a[i]+j)+<span class="number">1</span>;</span><br><span class="line">            ans=<span class="built_in">max</span>(ans,t);</span><br><span class="line">            <span class="built_in">add</span>(j+<span class="number">1</span>,a[i]+j,t);</span><br><span class="line">        }</span><br><span class="line">    }</span><br><span class="line">    cout&lt;&lt;ans;</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>

<hr>
<p><a target="_blank" rel="noopener" href="https://www.acwing.com/solution/content/105366/">AcWing 2978. 最长上升子序列 - AcWing</a></p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">1e5</span>+<span class="number">10</span>;</span><br><span class="line">vector&lt;<span class="type">int</span>&gt;a;</span><br><span class="line"><span class="type">int</span> n,tr[N],dp[N];</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">add</span><span class="params">(<span class="type">int</span> x,<span class="type">int</span> c)</span></span>{</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=x;i&lt;=n;i+=i&amp;-i)tr[i]=<span class="built_in">max</span>(tr[i],c);</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">sum</span><span class="params">(<span class="type">int</span> x)</span></span>{</span><br><span class="line">    <span class="type">int</span> ans=<span class="number">0</span>;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=x;i;i-=i&amp;-i)ans=<span class="built_in">max</span>(ans,tr[i]);</span><br><span class="line">    <span class="keyword">return</span> ans;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    cin&gt;&gt;n;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">        <span class="type">int</span> x;</span><br><span class="line">        cin&gt;&gt;x;</span><br><span class="line">        a.<span class="built_in">insert</span>(x+a.<span class="built_in">begin</span>(),i);</span><br><span class="line">    }</span><br><span class="line">    <span class="type">int</span> ans=<span class="number">0</span>;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">0</span>;i&lt;n;i++){</span><br><span class="line">        <span class="type">int</span> t=a[i];</span><br><span class="line">        dp[t]=<span class="built_in">sum</span>(t)+<span class="number">1</span>;</span><br><span class="line">        <span class="built_in">add</span>(t,dp[t]);</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">        dp[i]=<span class="built_in">max</span>(dp[i],dp[i<span class="number">-1</span>]);</span><br><span class="line">        cout&lt;&lt;dp[i]&lt;&lt;<span class="string">'\n'</span>;</span><br><span class="line">    }</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line">作者：我已经不想再做刺客了</span><br><span class="line">链接：https:<span class="comment">//www.acwing.com/solution/content/105366/</span></span><br><span class="line">来源：AcWing</span><br><span class="line">著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。</span><br></pre></td></tr></tbody></table></figure>

<hr>
<p><a target="_blank" rel="noopener" href="https://www.acwing.com/problem/content/description/1268/">1266. 校门外的树 - AcWing题库</a></p>
<p>很巧妙的思路<br>把区间想象成一条条线段<br>要求区间种数转化为求有多少个线段覆盖过这个区间<br>r之前的左端点数量减去l之前的右端点数量</p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;cstring&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;algorithm&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">1e5</span>+<span class="number">10</span>;</span><br><span class="line"><span class="type">int</span> n,m,l,r,t1[N],t2[N],op;</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">add</span><span class="params">(<span class="type">int</span> x,<span class="type">int</span> tr[])</span></span>{</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=x;i&lt;=n;i+=i&amp;-i)tr[i]+=<span class="number">1</span>;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">sum</span><span class="params">(<span class="type">int</span> x,<span class="type">int</span> tr[])</span></span>{</span><br><span class="line">    <span class="type">int</span> ans=<span class="number">0</span>;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=x;i;i-=i&amp;-i)ans+=tr[i];</span><br><span class="line">    <span class="keyword">return</span> ans;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    cin&gt;&gt;n&gt;&gt;m;</span><br><span class="line">    <span class="keyword">while</span>(m--){</span><br><span class="line">        cin&gt;&gt;op&gt;&gt;l&gt;&gt;r;</span><br><span class="line">        <span class="keyword">if</span>(op==<span class="number">1</span>){</span><br><span class="line">            <span class="built_in">add</span>(l,t1);</span><br><span class="line">            <span class="built_in">add</span>(r,t2);</span><br><span class="line">        }</span><br><span class="line">        <span class="keyword">else</span>{</span><br><span class="line">            cout&lt;&lt;<span class="built_in">sum</span>(r,t1)-<span class="built_in">sum</span>(l<span class="number">-1</span>,t2)&lt;&lt;<span class="string">'\n'</span>;</span><br><span class="line">        }</span><br><span class="line">    }</span><br><span class="line">}</span><br><span class="line"></span><br></pre></td></tr></tbody></table></figure>

<hr>
<p><a target="_blank" rel="noopener" href="https://www.acwing.com/problem/content/description/2955/">2952. 不等式组 - AcWing题库</a></p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> endl <span class="string">'\n'</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">2e6</span>+<span class="number">10</span>;</span><br><span class="line"><span class="type">int</span> n,t1[N],t2[N],ok,k[N],idx,vis[N],p[N];</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">add</span><span class="params">(<span class="type">int</span> tr[],<span class="type">int</span> x,<span class="type">int</span> c)</span></span>{</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=x;i&lt;N;i+=i&amp;-i)tr[i]+=c;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">sum</span><span class="params">(<span class="type">int</span> tr[],<span class="type">int</span> x)</span></span>{</span><br><span class="line">    <span class="type">int</span> ans=<span class="number">0</span>;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=x;i;i-=i&amp;-i)ans+=tr[i];</span><br><span class="line">    <span class="keyword">return</span> ans;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    ios::<span class="built_in">sync_with_stdio</span>(<span class="number">0</span>);</span><br><span class="line">    cin.<span class="built_in">tie</span>(<span class="number">0</span>);</span><br><span class="line">    cout.<span class="built_in">tie</span>(<span class="number">0</span>);</span><br><span class="line">    cin&gt;&gt;n;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">        string s;</span><br><span class="line">        cin&gt;&gt;s;</span><br><span class="line">        <span class="keyword">if</span>(s[<span class="number">0</span>]==<span class="string">'A'</span>){</span><br><span class="line">            <span class="type">int</span> a,b,c;</span><br><span class="line">            cin&gt;&gt;a&gt;&gt;b&gt;&gt;c;</span><br><span class="line">            <span class="keyword">if</span>(a==<span class="number">0</span>){</span><br><span class="line">                <span class="keyword">if</span>(b&gt;c){</span><br><span class="line">                    ok++;</span><br><span class="line">                    k[++idx]=<span class="number">1</span>;</span><br><span class="line">                }</span><br><span class="line">                <span class="keyword">else</span>{</span><br><span class="line">                    k[++idx]=<span class="number">0</span>;</span><br><span class="line">                }</span><br><span class="line">            }</span><br><span class="line">            <span class="keyword">if</span>(a&gt;<span class="number">0</span>){<span class="comment">// k&gt;x</span></span><br><span class="line">                <span class="type">int</span> x=<span class="built_in">floor</span>((<span class="number">1.0</span>*c-b)/a);</span><br><span class="line">                <span class="keyword">if</span>(x&lt;<span class="number">-1e6</span>){</span><br><span class="line">                    ok++;</span><br><span class="line">                    k[++idx]=<span class="number">1</span>;</span><br><span class="line">                }</span><br><span class="line">                <span class="keyword">else</span> <span class="keyword">if</span>(x&gt;<span class="number">1e6</span>){</span><br><span class="line">                    k[++idx]=<span class="number">0</span>;</span><br><span class="line">                }</span><br><span class="line">                <span class="keyword">else</span>{</span><br><span class="line">                    <span class="built_in">add</span>(t1,x+<span class="number">1e6</span>+<span class="number">1</span>,<span class="number">1</span>);</span><br><span class="line">                    k[++idx]=<span class="number">2</span>;</span><br><span class="line">                    p[idx]=x+<span class="number">1e6</span>+<span class="number">1</span>;</span><br><span class="line">                }</span><br><span class="line">            }</span><br><span class="line">            <span class="keyword">if</span>(a&lt;<span class="number">0</span>){<span class="comment">// k&lt;x</span></span><br><span class="line">                <span class="type">int</span> x=<span class="built_in">ceil</span>((<span class="number">1.0</span>*c-b)/a);</span><br><span class="line">                <span class="keyword">if</span>(x&gt;<span class="number">1e6</span>){</span><br><span class="line">                    ok++;</span><br><span class="line">                    k[++idx]=<span class="number">1</span>;</span><br><span class="line">                }</span><br><span class="line">                <span class="keyword">else</span> <span class="keyword">if</span>(x&lt;<span class="number">-1e6</span>){</span><br><span class="line">                    k[++idx]=<span class="number">0</span>;</span><br><span class="line">                }</span><br><span class="line">                <span class="keyword">else</span>{</span><br><span class="line">                    <span class="built_in">add</span>(t2,x+<span class="number">1e6</span>+<span class="number">1</span>,<span class="number">1</span>);</span><br><span class="line">                    k[++idx]=<span class="number">3</span>;</span><br><span class="line">                    p[idx]=x+<span class="number">1e6</span>+<span class="number">1</span>;</span><br><span class="line">                }</span><br><span class="line">            }</span><br><span class="line">        }</span><br><span class="line">        <span class="keyword">if</span>(s[<span class="number">0</span>]==<span class="string">'Q'</span>){</span><br><span class="line">            <span class="type">int</span> x;</span><br><span class="line">            cin&gt;&gt;x;</span><br><span class="line">            x+=<span class="number">1e6</span>+<span class="number">1</span>;</span><br><span class="line">            <span class="type">int</span> ans1=<span class="built_in">sum</span>(t1,x<span class="number">-1</span>);</span><br><span class="line">            <span class="type">int</span> ans2=<span class="built_in">sum</span>(t2,N<span class="number">-1</span>)-<span class="built_in">sum</span>(t2,x);</span><br><span class="line">            cout&lt;&lt;ans1+ans2+ok&lt;&lt;endl;</span><br><span class="line">        }</span><br><span class="line">        <span class="keyword">if</span>(s[<span class="number">0</span>]==<span class="string">'D'</span>){</span><br><span class="line">            <span class="type">int</span> x;</span><br><span class="line">            cin&gt;&gt;x;</span><br><span class="line">            <span class="keyword">if</span>(vis[x])<span class="keyword">continue</span>;</span><br><span class="line">            vis[x]=<span class="number">1</span>;</span><br><span class="line">            <span class="keyword">if</span>(k[x]==<span class="number">1</span>)ok--;</span><br><span class="line">            <span class="keyword">if</span>(k[x]==<span class="number">2</span>)<span class="built_in">add</span>(t1,p[x],<span class="number">-1</span>);</span><br><span class="line">            <span class="keyword">if</span>(k[x]==<span class="number">3</span>)<span class="built_in">add</span>(t2,p[x],<span class="number">-1</span>);</span><br><span class="line">        }</span><br><span class="line">    }</span><br><span class="line">}</span><br><span class="line"></span><br></pre></td></tr></tbody></table></figure>

<hr>
<p><a target="_blank" rel="noopener" href="https://www.acwing.com/problem/content/4084/">4081. 选数 - AcWing题库</a></p>
<p>混合背包dp</p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;cstring&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;algorithm&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">220</span>,M=<span class="number">200</span>*<span class="number">26</span>;</span><br><span class="line"><span class="meta">#<span class="keyword">define</span> int long long</span></span><br><span class="line"><span class="type">int</span> f[N][M];</span><br><span class="line"><span class="type">int</span> n,k;</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    cin&gt;&gt;n&gt;&gt;k;</span><br><span class="line">    <span class="built_in">memset</span>(f,<span class="number">-0x3f</span>,<span class="keyword">sizeof</span> f);</span><br><span class="line">    f[<span class="number">0</span>][<span class="number">0</span>]=<span class="number">0</span>;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">        <span class="type">int</span> a;</span><br><span class="line">        cin&gt;&gt;a;</span><br><span class="line">        </span><br><span class="line">        <span class="type">int</span> w=<span class="number">0</span>;</span><br><span class="line">        <span class="type">int</span> v=<span class="number">0</span>;</span><br><span class="line">        <span class="keyword">while</span>(a%<span class="number">5</span>==<span class="number">0</span>)a/=<span class="number">5</span>,w++;</span><br><span class="line">        <span class="keyword">while</span>(a%<span class="number">2</span>==<span class="number">0</span>)a/=<span class="number">2</span>,v++;</span><br><span class="line">        <span class="comment">//cout&lt;&lt;w&lt;&lt;" "&lt;&lt;v&lt;&lt;endl;</span></span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> j=k;j&gt;=<span class="number">1</span>;j--){</span><br><span class="line">            <span class="keyword">for</span>(<span class="type">int</span> t=M<span class="number">-1</span>;t&gt;=w;t--){</span><br><span class="line">                f[j][t]=<span class="built_in">max</span>(f[j][t],f[j<span class="number">-1</span>][t-w]+v);</span><br><span class="line">            }</span><br><span class="line">        }</span><br><span class="line">    }</span><br><span class="line">    <span class="type">int</span> ans=<span class="number">0</span>;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;M;i++)ans=<span class="built_in">max</span>(ans,<span class="built_in">min</span>(i,f[k][i]));</span><br><span class="line">    cout&lt;&lt;ans;</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>

<hr>
<p><a target="_blank" rel="noopener" href="https://www.acwing.com/problem/content/3284/">3281. 城市规划 - AcWing题库</a></p>
<p>树形dp 分组背包</p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;cstring&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;algorithm&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N = <span class="number">5e4</span>+<span class="number">10</span>,M=<span class="number">2</span>*N;</span><br><span class="line"><span class="type">const</span> <span class="type">long</span> <span class="type">long</span> INF=<span class="number">0x3f3f3f3f3f3f3f3f</span>;</span><br><span class="line"><span class="type">int</span> h[N],ne[M],e[M],idx,n,m,K;</span><br><span class="line"><span class="type">int</span> s[N];</span><br><span class="line"><span class="type">int</span> st[N];</span><br><span class="line"><span class="type">long</span> <span class="type">long</span> w[M];</span><br><span class="line"><span class="type">long</span> <span class="type">long</span> f[N][<span class="number">110</span>];<span class="comment">//f【u】【k】表示以u为根选k个点的最大值</span></span><br><span class="line"><span class="type">long</span> <span class="type">long</span> ans=INF;</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">add</span><span class="params">(<span class="type">int</span> a,<span class="type">int</span> b,<span class="type">int</span> c)</span></span>{</span><br><span class="line">    e[idx]=b,w[idx]=c,ne[idx]=h[a],h[a]=idx++;</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">void</span> <span class="title">dfs</span><span class="params">(<span class="type">int</span> u,<span class="type">int</span> fa)</span></span>{</span><br><span class="line">    f[u][<span class="number">0</span>]=<span class="number">0</span>;</span><br><span class="line">    <span class="keyword">if</span>(st[u])f[u][<span class="number">1</span>]=<span class="number">0</span>,s[u]=<span class="number">1</span>;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=h[u];~i;i=ne[i]){</span><br><span class="line">        <span class="type">int</span> j=e[i];</span><br><span class="line">        <span class="keyword">if</span>(j==fa)<span class="keyword">continue</span>;</span><br><span class="line">        <span class="built_in">dfs</span>(j,u);</span><br><span class="line">        s[u]+=s[j];</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> k=<span class="built_in">min</span>(s[u],K);k&gt;=<span class="number">0</span>;k--){</span><br><span class="line">            <span class="keyword">for</span>(<span class="type">int</span> x=<span class="number">0</span>;x&lt;=<span class="built_in">min</span>(k,s[j]);x++)</span><br><span class="line">            f[u][k]=<span class="built_in">min</span>(f[u][k],f[u][k-x]+f[j][x]+w[i]*x*(K-x));</span><br><span class="line">        }</span><br><span class="line">    }</span><br><span class="line">    ans=<span class="built_in">min</span>(ans,f[u][K]);</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    <span class="built_in">memset</span>(h, <span class="number">-1</span>, <span class="keyword">sizeof</span> h);</span><br><span class="line">    cin&gt;&gt;n&gt;&gt;m&gt;&gt;K;</span><br><span class="line">    <span class="keyword">while</span>(m--){</span><br><span class="line">        <span class="type">int</span> x;</span><br><span class="line">        <span class="built_in">scanf</span>(<span class="string">"%d"</span>,&amp;x);</span><br><span class="line">        st[x]=<span class="number">1</span>;</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;n;i++){</span><br><span class="line">        <span class="type">int</span> a,b,c;</span><br><span class="line">        <span class="built_in">scanf</span>(<span class="string">"%d %d %d"</span>,&amp;a,&amp;b,&amp;c);</span><br><span class="line">        <span class="built_in">add</span>(a,b,c);</span><br><span class="line">        <span class="built_in">add</span>(b,a,c);</span><br><span class="line">    }</span><br><span class="line">    <span class="comment">// for(int i=0;i&lt;N;i++){</span></span><br><span class="line">    <span class="comment">//     for(int j=0;j&lt;110;j++){</span></span><br><span class="line">    <span class="comment">//         f[i][j]=0x3f3f3f3f;</span></span><br><span class="line">    <span class="comment">//     }</span></span><br><span class="line">    <span class="comment">// }</span></span><br><span class="line">    <span class="built_in">memset</span>(f,<span class="number">0x3f3f</span>,<span class="keyword">sizeof</span> f);</span><br><span class="line">    <span class="built_in">dfs</span>(<span class="number">1</span>,<span class="number">-1</span>);</span><br><span class="line">    cout&lt;&lt;ans;</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>

<hr>
<p><a target="_blank" rel="noopener" href="https://ac.nowcoder.com/acm/contest/11226/E">E-禅_牛客小白月赛49 (nowcoder.com)</a></p>
<p>思维递推</p>
<p>从起点p向两边递推，考虑每个单调区间，这种做法是错误的</p>
<p>比如2 2 2 2 1 10 0</p>
<p>从最左边开始代价是最小的，会一直加</p>
<p>那么既然无法确定起点，如何处理这n方复杂度？</p>
<p>设dp【i】表示从点i开始的代价，考虑答案之间的递推关系</p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="meta">#<span class="keyword">define</span> int long long</span></span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">1e5</span>+<span class="number">10</span>;</span><br><span class="line"><span class="type">int</span> n,a[N],T,f[N];</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    ios::<span class="built_in">sync_with_stdio</span>(<span class="number">0</span>);</span><br><span class="line">    cin.<span class="built_in">tie</span>(<span class="number">0</span>);</span><br><span class="line">    cout.<span class="built_in">tie</span>(<span class="number">0</span>);</span><br><span class="line">    cin&gt;&gt;T;</span><br><span class="line">    <span class="keyword">while</span>(T--){</span><br><span class="line">        cin&gt;&gt;n;</span><br><span class="line">        <span class="type">int</span> p;</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">            cin&gt;&gt;a[i];</span><br><span class="line">            <span class="keyword">if</span>(a[i]==<span class="number">0</span>)p=i;</span><br><span class="line">        }</span><br><span class="line">        <span class="keyword">if</span>(n==<span class="number">1</span>){</span><br><span class="line">            cout&lt;&lt;<span class="string">"No Solution"</span>&lt;&lt;<span class="string">'\n'</span>;</span><br><span class="line">            <span class="keyword">continue</span>;</span><br><span class="line">        }</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++)f[i]=<span class="number">0</span>;</span><br><span class="line">        f[p<span class="number">-1</span>]=a[p<span class="number">-1</span>]+<span class="number">1</span>;</span><br><span class="line">        f[p+<span class="number">1</span>]=a[p+<span class="number">1</span>]+<span class="number">1</span>;</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> i=p+<span class="number">2</span>;i&lt;=n;i++)f[i]=<span class="built_in">max</span>(a[i]+<span class="number">1</span>,f[i<span class="number">-1</span>]-a[i]);</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> i=p<span class="number">-2</span>;i&gt;=<span class="number">1</span>;i--)f[i]=<span class="built_in">max</span>(a[i]+<span class="number">1</span>,f[i+<span class="number">1</span>]-a[i]);</span><br><span class="line">        <span class="type">int</span> ans=<span class="number">1e9</span>;</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">            <span class="keyword">if</span>(i==p)<span class="keyword">continue</span>;</span><br><span class="line">            ans=<span class="built_in">min</span>(ans,f[i]);</span><br><span class="line">        }</span><br><span class="line">        cout&lt;&lt;ans&lt;&lt;<span class="string">'\n'</span>;</span><br><span class="line">    }</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>

<hr>
<p>二维RMQ</p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">1100</span>;</span><br><span class="line"><span class="type">int</span> ma[N][N][<span class="number">11</span>],mi[N][N][<span class="number">11</span>],n,a[N][N],p,m,k;</span><br><span class="line"><span class="type">int</span> ans=<span class="number">1e9</span>;</span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">qmax</span><span class="params">(<span class="type">int</span> i,<span class="type">int</span> j)</span></span>{</span><br><span class="line">    <span class="type">int</span> ma1=<span class="built_in">max</span>(ma[i][j][k],ma[i+p-(<span class="number">1</span>&lt;&lt;k)][j+p-(<span class="number">1</span>&lt;&lt;k)][k]);</span><br><span class="line">    <span class="type">int</span> ma2=<span class="built_in">max</span>(ma[i+p-(<span class="number">1</span>&lt;&lt;k)][j][k],ma[i][j+p-(<span class="number">1</span>&lt;&lt;k)][k]);</span><br><span class="line">    <span class="keyword">return</span> <span class="built_in">max</span>(ma1,ma2);</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">qmin</span><span class="params">(<span class="type">int</span> i,<span class="type">int</span> j)</span></span>{</span><br><span class="line">    <span class="type">int</span> mi1=<span class="built_in">min</span>(mi[i][j][k],mi[i+p<span class="number">-1</span>-(<span class="number">1</span>&lt;&lt;k)+<span class="number">1</span>][j+p-(<span class="number">1</span>&lt;&lt;k)][k]);</span><br><span class="line">    <span class="type">int</span> mi2=<span class="built_in">min</span>(mi[i+p<span class="number">-1</span>-(<span class="number">1</span>&lt;&lt;k)+<span class="number">1</span>][j][k],mi[i][j+p-(<span class="number">1</span>&lt;&lt;k)][k]);</span><br><span class="line">    <span class="keyword">return</span> <span class="built_in">min</span>(mi1,mi2);</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    ios::<span class="built_in">sync_with_stdio</span>(<span class="number">0</span>);</span><br><span class="line">    cin.<span class="built_in">tie</span>(<span class="number">0</span>);</span><br><span class="line">    cout.<span class="built_in">tie</span>(<span class="number">0</span>);</span><br><span class="line">    cin&gt;&gt;n&gt;&gt;m&gt;&gt;p;k=<span class="built_in">log2</span>(p);</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> j=<span class="number">1</span>;j&lt;=m;j++){</span><br><span class="line">            cin&gt;&gt;a[i][j];</span><br><span class="line">            ma[i][j][<span class="number">0</span>]=a[i][j];</span><br><span class="line">            mi[i][j][<span class="number">0</span>]=a[i][j];</span><br><span class="line">        }</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> k=<span class="number">1</span>;k&lt;=<span class="number">10</span>;k++){</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i+(<span class="number">1</span>&lt;&lt;k<span class="number">-1</span>)&lt;=n;i++){</span><br><span class="line">            <span class="keyword">for</span>(<span class="type">int</span> j=<span class="number">1</span>;j+(<span class="number">1</span>&lt;&lt;k<span class="number">-1</span>)&lt;=m;j++){</span><br><span class="line">                <span class="type">int</span> ma1=<span class="built_in">max</span>(ma[i][j][k<span class="number">-1</span>],ma[i+(<span class="number">1</span>&lt;&lt;k<span class="number">-1</span>)][j+(<span class="number">1</span>&lt;&lt;k<span class="number">-1</span>)][k<span class="number">-1</span>]);</span><br><span class="line">                <span class="type">int</span> ma2=<span class="built_in">max</span>(ma[i+(<span class="number">1</span>&lt;&lt;k<span class="number">-1</span>)][j][k<span class="number">-1</span>],ma[i][j+(<span class="number">1</span>&lt;&lt;k<span class="number">-1</span>)][k<span class="number">-1</span>]);</span><br><span class="line">                ma[i][j][k]=<span class="built_in">max</span>(ma1,ma2);</span><br><span class="line">                <span class="type">int</span> mi1=<span class="built_in">min</span>(mi[i][j][k<span class="number">-1</span>],mi[i+(<span class="number">1</span>&lt;&lt;k<span class="number">-1</span>)][j+(<span class="number">1</span>&lt;&lt;k<span class="number">-1</span>)][k<span class="number">-1</span>]);</span><br><span class="line">                <span class="type">int</span> mi2=<span class="built_in">min</span>(mi[i+(<span class="number">1</span>&lt;&lt;k<span class="number">-1</span>)][j][k<span class="number">-1</span>],mi[i][j+(<span class="number">1</span>&lt;&lt;k<span class="number">-1</span>)][k<span class="number">-1</span>]);</span><br><span class="line">                mi[i][j][k]=<span class="built_in">min</span>(mi1,mi2);</span><br><span class="line">            }</span><br><span class="line">        }</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i+p<span class="number">-1</span>&lt;=n;i++){</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> j=<span class="number">1</span>;j+p<span class="number">-1</span>&lt;=m;j++){</span><br><span class="line">            ans=<span class="built_in">min</span>(ans,<span class="built_in">qmax</span>(i,j)-<span class="built_in">qmin</span>(i,j));</span><br><span class="line">        }</span><br><span class="line">    }</span><br><span class="line">    </span><br><span class="line">    cout&lt;&lt;ans;</span><br><span class="line">    <span class="comment">//cout&lt;&lt;ma[1][2][3];</span></span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>

<hr>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="meta">#<span class="keyword">define</span> int long long</span></span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">2e5</span>+<span class="number">10</span>;</span><br><span class="line"><span class="type">int</span> n,m;</span><br><span class="line"><span class="type">int</span> ru[N],chu[N],vis[N];</span><br><span class="line">vector&lt;<span class="type">int</span>&gt;g[N];</span><br><span class="line"><span class="type">int</span> f[N],ans=<span class="number">1</span>;</span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">dfs</span><span class="params">(<span class="type">int</span> u)</span></span>{</span><br><span class="line">    <span class="keyword">if</span>(chu[u]&lt;=<span class="number">1</span>)<span class="keyword">return</span> f[u]=<span class="number">1</span>;</span><br><span class="line">    <span class="keyword">if</span>(f[u])<span class="keyword">return</span> f[u];</span><br><span class="line">    f[u]=<span class="number">1</span>;</span><br><span class="line">    <span class="keyword">for</span>(<span class="keyword">auto</span> j:g[u]){</span><br><span class="line">        <span class="built_in">dfs</span>(j);</span><br><span class="line">        <span class="keyword">if</span>(ru[j]&gt;=<span class="number">2</span>)f[u]=<span class="built_in">max</span>(f[u],f[j]+<span class="number">1</span>);</span><br><span class="line">    }</span><br><span class="line">    ans=<span class="built_in">max</span>(ans,f[u]);</span><br><span class="line">    <span class="keyword">return</span> f[u];</span><br><span class="line">}</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    ios::<span class="built_in">sync_with_stdio</span>(<span class="number">0</span>);</span><br><span class="line">    cin&gt;&gt;n&gt;&gt;m;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=m;i++){</span><br><span class="line">        <span class="type">int</span> a,b;</span><br><span class="line">        cin&gt;&gt;a&gt;&gt;b;</span><br><span class="line">        chu[a]++,ru[b]++;</span><br><span class="line">        g[a].<span class="built_in">push_back</span>(b);</span><br><span class="line">    }</span><br><span class="line">    <span class="comment">//如果我的出度&gt;1则可以出发，如果你的入度&gt;1则可以到达</span></span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++)<span class="built_in">dfs</span>(i);</span><br><span class="line">    cout&lt;&lt;ans;</span><br><span class="line">    </span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>

<hr>
<p><a target="_blank" rel="noopener" href="https://ac.nowcoder.com/acm/contest/19483/F">F-牛牛的猜球游戏_牛客竞赛数据结构专题班前缀和练习题 (nowcoder.com)</a></p>
<figure class="highlight cpp"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;bits/stdc++.h&gt;</span></span></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"><span class="type">const</span> <span class="type">int</span> N=<span class="number">1e5</span>+<span class="number">10</span>;</span><br><span class="line"><span class="type">int</span> f[N][<span class="number">10</span>],ans[N];</span><br><span class="line"><span class="type">int</span> n,m;</span><br><span class="line"><span class="function"><span class="type">signed</span> <span class="title">main</span><span class="params">()</span></span>{</span><br><span class="line">    ios::<span class="built_in">sync_with_stdio</span>(<span class="number">0</span>);</span><br><span class="line">    cin.<span class="built_in">tie</span>(<span class="number">0</span>);</span><br><span class="line">    cout.<span class="built_in">tie</span>(<span class="number">0</span>);</span><br><span class="line">    cin&gt;&gt;n&gt;&gt;m;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">0</span>;i&lt;<span class="number">10</span>;i++)f[<span class="number">0</span>][i]=i;</span><br><span class="line">    <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">1</span>;i&lt;=n;i++){</span><br><span class="line">        <span class="type">int</span> l,r;</span><br><span class="line">        cin&gt;&gt;l&gt;&gt;r;</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> j=<span class="number">0</span>;j&lt;<span class="number">10</span>;j++)f[i][j]=f[i<span class="number">-1</span>][j];</span><br><span class="line">        <span class="built_in">swap</span>(f[i][l],f[i][r]);</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">while</span>(m--){</span><br><span class="line">        <span class="type">int</span> l,r;</span><br><span class="line">        cin&gt;&gt;l&gt;&gt;r;</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">0</span>;i&lt;<span class="number">10</span>;i++)ans[  f[l<span class="number">-1</span>][i]  ]=i;</span><br><span class="line">        <span class="keyword">for</span>(<span class="type">int</span> i=<span class="number">0</span>;i&lt;<span class="number">10</span>;i++)cout&lt;&lt;ans[  f[r][i]  ]&lt;&lt;<span class="string">" "</span>;</span><br><span class="line">        cout&lt;&lt;<span class="string">'\n'</span>;</span><br><span class="line">    }</span><br><span class="line">}</span><br></pre></td></tr></tbody></table></figure>


                
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